The present disclosure relates to ventricular assist devices (“VADs”), to components useful in such devices, and to methods of using the same.
In certain disease states, the heart lacks sufficient pumping capacity to meet the needs of the body. This inadequacy can be alleviated by providing a mechanical pumping device, such as a VAD, to supplement the pumping action of the heart. Considerable effort has been devoted to providing a VAD which can be implanted and which can remain in operation for months or years to keep the patient alive while the heart heals, or which can remain in operation permanently or until a suitable donor heart becomes available if the heart does not heal.
A VAD is typically connected to the heart, most commonly to the left ventricle. For example, a VAD may include a pump which is installed in the body outside of the heart. The VAD may have an inlet cannula connected to the interior of the left ventricle and connected to the intake of the pump. The VAD may also include an outlet tube connected between the outlet of the pump and the aorta. Once connected, the VAD and the heart both pump blood from the left ventricle to the aorta. Some VADs may include a fluid intake or inlet within a chamber of the heart, such within the left ventricle. For example, U.S. Patent Publication No. 2009/0203957, the disclosure of which is hereby incorporated by reference herein, discloses a VAD with an inlet positioned within the left ventricle.
With such systems, depending on the particular positioning of the inlet, the operating parameters of the VAD, and the anatomy of the patient, a situation may arise in which heart tissue is pulled into the pump inlet. For example, a wall of the ventricle, the papillary muscles, or chordae tendinae may be sucked partially into the inlet. In other situations, such as when there is relatively little volume of fluid in the left ventricle, the walls of the left ventricle may be caused to partially collapse due to forces caused by the pump. Such a situation may be described as a suction condition. The scenarios described above may cause the pump to malfunction and may cause injury to the patient.
Patients with heart failure may have reduced left ventricular diameters that reduce the ability of the heart to fill during diastole. For example, some patients may have conditions such as hypertrophic cardiomyopathy in which walls of the heart become thick and rigid, or diastolic dysfunction in which the ventricle does not relax properly during diastole. In these patients, the ventricle may not fill with as much blood as in a healthy heart. Using existing VADs in patients with these types of conditions may be difficult.